[Relative importance of the mating stimulations: courtship, copulation and insemination on the ovarian production of Drosophila melanogaster].
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The direct and indirect consequences of female copulatory behaviour for copulation success have seldom been quantified. In feral fowl, most copulations were forced by males and copulation success was determined by two factors. First, female differential resistance and solicitation directly affected copulation success and were displayed non-randomly with respect to male social status. Second, another female copulatory behaviour, the distress call, had an indirect effect on both copulation success and the quality of copulation partners. Distress calls triggered male attention to a copulation, which increased the probability of higher-ranking males than the copulating male disrupting the copulation and inseminating the calling female. Females preferentially uttered distress calls when mounted by low-ranking males. Both copulation resistance and distress calling influenced copulation success, but only distress calling increased the probability of copulation disruption by other males. Consistent with the effect of direct selection, differential distress calling indirectly biased copulation success in favour of dominant males. Female fowl may thus ameliorate the effect of male sexual coercion by manipulating male behaviour.
We tested the hypothesis that expression of sexual behavior in bulls is affected by the manner in which they are exposed to unrestrained, sexually receptive females. Twelve Angus bulls were used in a crossover design involving two treatments, each tested four times for a total of eight tests for each bull. Sexual interactions were quantified for each of four, 30-min periods under the following treatments: 1) exposure to each of four estrual females in sequence (SEQ); or 2) exposure to four estrual females as a group (GRP). Bulls were blocked into three testing groups, the order of which was stratified across eight test days. The order in which bulls were tested on a particular day had no effect on bulls' expression of mount interactions, or flehmen responses, suggesting that each group of bulls had similar sexual motivation at the beginning of each test. However, the bull testing order x treatment x time interaction influenced mounting interval (P = 0.08), copulation frequency (P <0.05), and copulation success ratio (P <0.05). When bulls were in GRP and tested first on test days, more (P <0.05) copulations were distributed to the first three females encountered compared with either the fourth female (P <0.05) or to each of the other females in SEQ (P <0.05). During later tests, other bulls in GRP were not able to copulate as frequently (P <0.05) with each female, displayed lower (P <0.05) copulation success ratios, and were allowed copulations by fewer (P <0.05) females during each 30-min test. When bulls were in SEQ, they displayed similar numbers of copulations regardless of the order in which they were tested, and had stable mounting intervals; however, copulation success ratio decreased (P <0.05) more rapidly during subsequent tests. Flehmen responses were initially displayed more frequently (P <0.05) when bulls were in GRP, but this effect diminished during subsequent 30-min tests. In conclusion, exposure of bulls to GRP induced greater sexual responsiveness than SEQ; however, this effect was due to enhanced sexual activity during the early stages of sexual encounters and with females that were not recently mated. Interestingly, bulls seem to repeatedly copulate with each individual female until, apparently, female sexual receptivity became attenuated. Thereafter, recently mated females allowed fewer episodes of repeated copulations, but they did not completely cease copulating with novel bulls.
Tufted capuchin monkeys (Cebus apella) provide an extreme example of active female sexual solicitation of males. In spite of being targeted by females for sex, males may delay copulation for hours or days. Data were collected on the sexual interactions in one wild capuchin group at the Estação Biológica de Caratinga in Brazil from September 1996 to August 1997. All successful conceptions during this year occurred in the dry season, yet sexual behavior was observed during 9 months of the year. This study tested whether male sexual response to female proceptivity was seasonally-mediated. Male consortship participation, solicitation of females, latency to copulation, and copulation frequency were compared between fertile and nonconceptive females. Seasonal patterns in copulation interference, mating style, and alternative mating strategies were also examined. Thirty-two copulations were observed. The alpha male was solicited for significantly more consortship days per female, but his mating success, in terms of copulation frequency, did not differ from that of two other adult males in the group. In the dry season, when the females were fertile, the males showed increased contest competition for mates, a higher frequency of alternative mating strategies against copulation interference, and increased monitoring of the females' condition. However, contrary to expectations, the alpha male's latency to copulation was significantly longer in the fertile season than in the nonconceptive months, and no males were observed to mate more than one time per day, even at the conceptive peak. Male mating strategies were affected by both season and rank, and there was evidence for reproductive constraints on males throughout the year. Limited male ejaculatory capacity and male choice in the timing of copulations within female proceptive phases may both be important factors in driving the sexual dynamics of this species.